The invention relates to a device for non-contact measurement of the surface of a three-dimensional object.
Such devices are particularly used in mechanical engineering, car manufacture, ceramics industry, footwear industry, jewelry industry, dental surgery and human medicine and in other fields.
The increasing requirements for a largely complete quality control during the running production process as well as after digitizing the three-dimensional form of the prototypes make plotting the surface topographies one's measuring task which is more and more frequently set. Hence, the task is set to determine the coordinates of single points of the surface of objects to be measured during a short time.
There are different approaches to solve both the time and scanning problems by the application of optical measuring systems. The advantage of optical measuring systems is in the non-contact and thus reactionless measurement as well as in that the information on the object are present in an illustrative form and thus in an easily understood manner. These optical measuring systems comprise the fringe projection method including Gray-Code technique, the moir, technique, holographic and speckle contouring as well as photogrammetry. It is typical for such methods that the measured variables of interest, the three-dimensional coordinates of the surfaces of objects are indirectly determined from the phase measured variables in images of intersection lines of patterns of light such as fringe patterns projected on to the object, from phase measured variables of the moir, technique, from the coordinates of the piercing points of observing beams through the receiving area and/or from parameters which characterize the geometry of the set-up of measuring instruments, i.e. the light sources, optical components as well as the image recording device. With known geometrical parameters of the set-up of measuring instruments the coordinates of the measuring points on the surface of the object can be calculated in a sensor system of coordinates by means of triangulation from three phase measured variables being linearly independent from each other and/or respective image and pixel coordinates. For generating the patterns of light different projection systems are employed such as programmable LCD projectors, slidable glass supports having different grid structures within a projector, the combination between a grid which can be electrically switched and a mechanical shifting device or the projection of single grids based on glass supports as well.